Lateral torsional buckling strength of steel i-beams within preflexed beams in pre-bending stage

Abstract

Attention should be paid to the lateral torsional buckling (LTB) of steel I-beams in pre-bending stage for the usage of preflexed beams. This paper develops analytical and numerical models for predicting LTB strength of steel I-beams arranged with different numbers of lateral braces and subjected to two movable concentrated loads in pre-bending stage. The different out-of-plane deformations of beam segments under assumed and actual conditions caused by bending moment distribution were considered, and the modified Rayleigh-Ritz method was proposed based on the constraint effect of adjacent beam segments. ABAQUS 2017 program was used for finite element analysis (FEA), and then have a comparison with the theoretical analysis. Additionally, LTB strength of steel I-beams with different parameters were investigated, and the effect of every selected parameter was described. The comparison results show that the modified Rayleigh-Ritz method has better applicability and accuracy under different parameters than the traditional Rayleigh-Ritz method, which can be used for selecting parameters and predicting LTB strength of steel I-beams in pre-bending stage.